Field of the Invention
The invention relates to lighting configurations and, more particularly, to configurations primarily used as decorative assemblies in the form of flexible LED linear lights with diffusion properties.
Background Art
Various types of electrical lighting systems have been known and developed throughout the years since the early days of Edison's inventions. Originally, most electrical lighting (in the form of light bulbs and the like) existed for functional and generally practical uses, namely to provide illumination in what would otherwise be relatively dark spacial areas. As electrical lighting development matured, alternatives to conventional light bulbs were the subject of numerous inventions and other developments. For example, and is apparent in many retail establishments, fluorescent lighting was developed. Fluorescent lamps or tubes are typically relatively low pressure mercury-vapor gas discharge lamps which use fluorescence to produce visible light. Electrical current in the gas excites mercury vapor which produces short-wave ultraviolet light. It then causes a phosphor coating on the inside of the bulb to fluoresce, thereby producing visible light. Fluorescent lighting typically converts electrical power into usable light much more efficiently than incandescent lamps.
Although fluorescent lighting is used in both retail and commercial establishments, they have some disadvantages. Often, fluorescent light fittings are relatively bulky, and inconvenient for use in restricted spaces such as display cases and the like. Also, such light fittings can have a relatively short life and require frequent maintenance. Still further, fluorescent lighting can operate at a somewhat hazardous high voltage, with respect to the requirements of a starter/ballast.
Fluorescent lamps and gas discharge lamps have existed for a significant period of time, originally being displayed by Tesla in 1893 at the World Columbian Exhibition. In 1897, Nernst invented and patented his incandescent lamp, based primarily on solid state electrical lights.
Other significant developments occurred throughout the 20th century. In 1901, Peter Hewitt demonstrated a mercury vapor lamp. In 1981, Philips first marketed what was characterized as compact fluorescent energy saving lamps, with integrated conventional ballast. In 1985, Osram, in competition with Philips, started to market an electronic energy saving lamp. Shortly thereafter, the “white” sodium vapor lamp was introduced.
Other developments included ceramic metal halide lamps (originally developed by a team at Nela Parc in 1992). In 1994, T-5 lamps having a cool tip were introduced and became the most popular fluorescent lamps, with what was considered to be excellent color rendering. Also developed in this timeframe was the first commercial sulfur lamp.
In addition to the foregoing developments, Nick Hollnyak is credited with developing the first practical spectrum Light Emitting Diode (LED) in 1962. However, in fact, the general LED has been around, at least at a theoretical level, since initially discovered back in the first decade of the 20th century.
Hollnyak is typically credited as the father of the modern LED. An LED can generally be defined as a semi-conductor light source. When an LED is switched on, electrons are able to recombine with holes within the device, releasing energy in the form of photons. This effect is commonly referred to as electroluminescence and the color of the light is determined by the energy gap of the semi-conductor. LEDs present many advantages over incandescent light sources, including lower energy consumption, longer lifetime, improved physical robustness, smaller size, and faster switching. LEDs have been used in numerous applications, as diverse as aviation lighting, digital microscopes, automotive lighting, advertising, general lighting, and traffic signals. Their high switching rates are also useful in advanced communications technology.
One use for LED configurations which has become more popular during the last several years is the application of LEDs for lighting fixtures which may provide some functional illumination, but also may primarily act as decorative lighting assemblies. LED configurations which are useful for decorative lighting assemblies are rigid LED linear lights and flexible LED rope lights, including both indoor and outdoor applications. Rigid LED lights comprise LEDs conventionally mounted on a structure which links the LEDs together both electrically and physically. A housing surrounding the LED strip often consists of a rigid PVC material. These rigid light strings are typically mounted through adhesive backings to the desired structures. In contrast, and in accordance with the invention as described in the section titled “Detailed Description of the Preferred Embodiments” and defined in the section titled “Claims”, the invention relates to a “flexible LED linear light assembly” which utilizes a series of spaced apart and electrically linked LEDs which are mounted on a flexible printed circuit board. In addition to the flexible printed circuit board, the flexible LED linear light assembly further consists of a flexible housing or lens, as opposed to the use of any type of rigid housing. Further, with flexible LED linear light assemblies in accordance with the invention, the LEDs may be surface mounted to a flexible polymer PCB. In contrast, flexible LED rope lights are assembled such that the LEDs are often attached to two buss wires.
Flexible LED linear lights in accordance with the invention can be utilized in many applications. For example, flexible LED linear lights in accordance with the invention can be applied as indoor lighting for outlining the edges of a kitchen counter, under-lighting baseboards in a movie theatre and similar applications. Flexible LED linear lights can also be utilized as outdoor lighting, including staircase lighting, outdoor patio or deck lighting, signage and outdoor artistic displays. Flexible LED linear lights are also suitable for use around a garden, pool, driveway, shed or the like. In addition, during holiday seasons, flexible LED linear lights in accordance with the invention can be readily used to create artistic messages or designs utilizing different colors and patterns.
One issue which arises with respect to the use of LEDs, and particularly a string of LEDs, relates to the concept that individual LEDs are effectively unidirectional hard-point light sources. Accordingly, an LED light string, standing alone, can exhibit both dark zones and “hot spots.” It should be mentioned at this point that hot spots are not evident with the use of either florescent or neon tube lights. However, in other lighting assemblies which may be used, for example, as “under cabinet” lighting, hot spots can often show up on the counter top. Correspondingly, in wall wash lighting, the hot spots can show up as irregularities in the light patterns. Such hot spots have become more of a problem as LED brightness has increased in commercial products. To overcome these problems of LED hot spots, dark zones and overall light transmission uniformity, the LED lighting assembly can include a diffusion apparatus. The concept of diffusion for lighting apparatus relates to the transmission or reflection of electromagnetic radiation in the form of light, where the radiation is scattered in a number of different directions, and not totally reflected or refracted. Such activity is also referred to as “scattering” of light. The diffusion can also be referred to as a reflection or refraction of light (or other electromagnetic radiation) from an irregular surface or an erratic dispersion through a surface or other medium. Some of the assemblies which currently exist use what is characterized as “uniformity tape,” which is a microstructured thin-shell mechanism for mixing and diffusing the light generated by the LEDs. It is particularly utilized in edge-lit digital displays, including monitors, televisions and signage. In these systems, light generated by the LEDs is attempted to be spread evenly to all parts of a display by a light guide, which may typically consist of a plate of polymethyl methacrylate. This guide transports light by total internal reflection, commonly referred as “TIR.” Extraction patterns on the surface of the light guide will mete out the light and generate a uniform brightness distribution. However, even with the light guide, dark zones can be noticeable along the injection edge closest to the LEDs. Further, and somewhat obvious, dark zones will also influence the spacing between LEDs, which limits the ability of designers to reduce the number of LEDs in a display, despite what would exist as far as cost advantages and increased energy efficiency. Further, light-mixing of certain known light guides makes digital displays highly sensitive to variations in LED color and brightness. Still further, closely packed LEDs can also create thermal management issues.
In addition to issues associated with uniformity of diffusion for LED light strings and similar assemblies, issues also exist with respect to facilitating manufacture of diffused LED light strings. For example, the manufacturing process should preferably facilitate assembly of the LED light strings in positions desired within a housing comprising, for example, a translucent housing material. In addition, one problem which has existed in known assemblies relates to the fact that various LED lighting assemblies utilizing flexible LED light strings also utilize end cap structures which secure the ends of elongated housing and provide entry of electrical power into the housing interior for connection with the light string. During the manufacturing process, it is sometimes difficult to appropriately mount the end cap structure to the ends of the housing, with respect to their interfaces. For example, with certain mounting processes, areas which could be characterized as “steps” or other non-linear or non-continuous edges or other projections can be formed between the housing structure and the end cap structures. These formations can increase the difficulty of properly mounting the end cap structures to the housing, and can also take away from the overall aesthetics of the diffused light string assembly.
With the foregoing issues in mind, reference is now made to a number of patents and patent application publications which are associated with LED strings, translucent housing members and/or other optical and electrical principles. For example, the commonly assigned U.S. Patent Application Publication to VanDuinen et al., 2012/0170258, is directed to displays of case lighting having a lens with integrally formed features on its interior for purposes of mechanically retaining LED units within the interior. At least one of the LED units consists of a base and diodes mechanically engaged on a rigid PCB with integrally formed features of the lens. An electrical connector is provided to connect the LED units to a power source. At least one end cap incorporates the electrical connector. For purposes of sealing the assembly, a boot seal is provided for sealing the electrical connector and a plug cover is used to cover any unused electrical connectors which may be provided. An adhesive is used to secure the end cover to the lens and seal the connection therebetween. With this configuration, the lighting assembly is suitable for use in wet or potentially explosive environments.
Turning to other specific patent references, a number of the references teach general concepts associated with the use of LED light strings within translucent housing members. For example, U.S. Patent to Cleaver et al., U.S. Pat. No. 8,322,883, discloses an illumination device having a rod-like member with a light receiving surface and a light-emitting surface. An elongated light source extends along a position adjacent to a light receiving surface of the member, such that the light entering the member from the elongated light source and through the light receiving surface is scattered. This scattering process causes a light intensity pattern which appears substantially uniform along the light-emitting surface of the rod-like member. The Cleaver et al. patent is specifically directed to neon lighting, and has relevance only with respect to its discussion of point light sources and advantages of providing a light intensity pattern which appears substantially uniform along a light-emitting surface of a rigid rod-like member.
The U.S. Patent to Ikeda, U.S. Pat. No. 7,253,444, is directed to a structure and process for manufacturing the structure which consists of a casing for use with a light-emitting unit. Ikeda discloses the concept of the unit having a substrate and light-emitting diodes housed within the casing. When silicone is injected through an injection opening, the silicone flows through the entirety of the housing, and then overflows from a discharge opening. The purpose for the silicone injection is to “push outside” air or air bubbles which have formed within the light-emitting unit.
The U.S. Patent Application Publication to Ishibashi et al., 2013/0107526 is directed to the use of cluster boards, with a series of LEDs mounted in an array on central parts of the boards in a transverse direction of the boards. The LED mounting portions in the first and second boards are formed so as to be bendable.
The U.S. Patent Application Publication to Mostoller et al., 2010/0201239 is directed specifically to an end cap configuration for a light tube having a LED light string. The end cap assembly includes an end cap connector extending from the body and holding contacts with first mating portions configured so as to be electrically connected to the circuit board, and second mating portions configured to electrically connect to the socket connector. The end cap assemblies of Mostoller et al. do not provide for any flush mounting of the cap with an outer surface of the housing profile.
The U.S. Patent to Goto, U.S. Pat. No. 7,045,971, is directed to an illuminating apparatus having full-color LEDs, with a controller and power supply cable. The light emitting unit includes a series of light emitting elements having different emission colors. Other than showing a string of full-color LEDs for decorative purposes, the Goto patent does not appear to have any significant relevance.
The U.S. Patent Application Publication to Kelly, et al., No. 2008/0007945 is directed to a cabinet illuminator having a pair of LED lines. The LED lines are found in an elongated body having a heat transfer portion for conduction of heat from the LEDs to the outer surface of the body. An engagement configuration exists in the ends of the body for engagement with other structural members of a display cabinet. The end connectors do not appear relevant to the ITC invention.
The U.S. Patent to Terada, et al., U.S. Pat. No. 7,758,230, discloses a spread illuminating apparatus having an LED, with a transparent resin plate and a light reflecting sheet. The plate includes slits adapted to have flap portions of the light reflecting sheet inserted therein. An adhesive tape with flexibility is placed along at least one flat portion of the reflecting sheet, so as to cover at least one slit of the resin plate. The light reflecting sheet is prevented from warping or undulating in spite of the difference in thermal expansion coefficients between the materials of the resin plate and the reflecting sheet. Light emitted from the LED and traveling in the resin plate is totally reflected by the flat portions, and thereby prevented from leaking from the outer side surfaces of the resin plate.
Other references include the following:                The U.S. Patent Application Publication to Berger, et al., 2009/0073692 is directed to a modular and expandable lighting system.        The U.S. Patent Application Publication to Payne, 2008/0159694 is directed to a lens configuration for optical touch systems.        The U.S. Patent to Shimura, et al., U.S. Pat. No. 7,815,359, is directed to a spread illuminating apparatus utilizing a transparent resin plate.        The U.S. Patent to Terada, et al., U.S. Pat. No. 7,726,868, is directed to a spread illuminating apparatus, and is primarily related to a method of injection molding for the transparent resin plate.        The U.S. Patent to Kawakami, U.S. Pat. No. 7,160,019, is directed to a side-lighting surface light source device, along with a manufacturing method for the same. The device includes a light source, reflective member, and light guide plate.        
The following patents are directed to various types of display devices utilizing LED configurations.                Song, et al., Publication No. 2013/0082989;        Kawaguchi, et al., U.S. Pat. No. 8,134,675;        Myburgh, U.S. Publication No. 2004/0228135.        
Other patents utilizing LED string apparatus include the following:                Sadwick, et al., U.S. Pat. No. 7,709,292;        Rawson, et al., U.S. Pat. No. 3,984,923;        Aronson, et al., U.S. Pat. No. 4,488,237;        Brand, U.S. Pat. No. 5,266,123;        Brand, U.S. Pat. No. 5,363,865;        Myburgh, U.S. Pat. No. 6,827,472;        Wood, U.S. Pat. No. 4,159,490;        Bettis, 2004/0184288;        Yoshida, et al., 2013/018352;        Tsai, et al., U.S. Pat. No. 7,768,658.        